Sensing device to measure the speed of rotation of drilling turbines

ABSTRACT

This invention concerns a sensing device to measure the speed of rotation of a drilling turbine, used with a device to transmit signals from the bottom of the well to the surface. This sensing device consists of a detector working with a mobile magnetic flux transducer, a tube containing the leads, and a male plug for connection with the transmitting device, with a flange at the top end of the tube which rests on the conical base of the turbine neck. The device, because of its design, offers the advantages of a removable unit, which will fit any type of turbine.

United States atent 1191 Le Peuvedic et all.

[ July 9, 1974 [54] SENSING DEVICE TO MEASURE 3,036,460 5/l962 White et al. 324/l68 UX SPEED OF ROTATHON 0F DLLING TURBINES Primary Examiner-Jerry W. Myracle [75] Inventors: Jean-Pierre Le Peuvedic; Jacques Attorney Agent or Flrm Bnsebols & Kruger Tinchon, both of Pau, France 57 ABS CT [73] Assignee: Societe Anonyme dite: Societe i L I Nationale des paroles dAquimine This invention concerns a sensing device to measure Tour Aquitaine, Paris, France the speed of rotation of a drilling turbine, used with a device to transmit signals from the bottom of the well [22] Filed: May 30, 1972 to the surface [21 Appl. No.: 257,763 This sensing device consists of a detector working with a mobile magnetic flux transducer, a tube containing the leads, and a male plug for connection with the i 'g transmitting device, with a flange at the top end of the [58] Fie'ld 175/40 I tube which rests on the conical base of the turbine 324/166, 167, 168 neckv The device, because of its design, offers the 5 R f n Cited advantages of a removable unit, which will fit any type UNITED STATES PATENTS of 2,985,829 5/1961 Swift 324/166 4 Claims, 3 Drawing Figures PATENTED JUL 91974 SHEET 2 UF 2 SENSING DEVICE TO MEASURE THE SPEED OF ROTATION OF DRILLING TURBINES This invention concerns a sensing device or transducer to supply signals representing the speed of rotation of the turbines often used as motors at the bottom of deep wells during drilling. When the ground is compact and homogeneous, diamond tools are usually preferable for drilling, since they have a much longer useful life than cutter-wheel tools, thereby saving time on tool-changing, which can often be a lengthy business in deep wells. An electric or hydraulic motor at the bottom of the well is a convenient way of driving such tools, allowing the higher rotational speeds required for this type of tool, and much greater efficiency, by eliminating friction along the sides of the well, which is unavoidable with the normal method of direct drive by means of rods.

A hydraulic motor or drilling turbine is usually preferred, because it is fully compatible with standard drilling equipment, particularly pumps and rods, and does not require any electrical cables, which are hard to keep properly insulated. In this type of motor, the turbine and its revolving blading are fixed to the tool, and the drilling mud or fluid is discharged under pressure inside the rods carrying the turbine and tool, driving the blading round before passing through apertures in the tool to reach the bottom of the well. The mud, conveying the material resulting from the work of the tool, then rises again, flowing upwards through the space left clear between the sides of the newly drilled shaft and the rods carrying the turbine and tool. Thicker pipes, known as the drill collars, are often placed between the turbine anddrill string, to keep the rods stretched while allowing sufficient weight to be placed on the tool to obtain proper drilling speed.

A major drawback in the use of well-bottom motors is the difficulty of finding out the speed of rotation of the driving shaft. Drilling becomes difficult, since many factors can affect the speed of the tool, such as variations in the hardness of the ground being drilled, or fluctuations in the output of mud-pumps.

Unless the speed of rotation of the tool is known, it is not possible to tell whether a drop in thespeed of drilling is caused by a localized changein the nature of the ground or a drop in the rotational speed of the turbine, or even premature wear on the tool.

Several types of devices to measure the speed of rotation of such motors, and transmit the results of measurements to the surface, already exist, based on electromagnetic or hydraulic principles. Those based on electromagnetic principles are usually unaffected by mechanical wear on parts in contact with drilling fluid, and the electrical signal they provide is more suitable for bottom-to-surface transmission devices.

Existing devices for measuring the speed of rotation of motors at the bottom of wells, however have the drawback of involving the use of components that are specific to one type of turbine, so that they are not adaptable to different types of turbines with variable diameters or operating with different mud tlows.

The present invention offers a simple, removable unit which can be fitted to any type of drilling turbine and can be used together with an independent system for transmitting signals to the surface. as described in Pat. application Nos. 162,558 and 206,367 or any other type of independent well-bottom system not requiring a particular material connection with the surface.

More specifically, it concerns a device to detect the speed of rotation of a drilling turbine, consisting of a unit which fits inside the upper end of the turbine casing, will fit any type of turbine, can be connected by a plug to a device to transmit signals from the bottom of the well to the surface, and consisting of a metal tube containing leads, with a centring component which slides freely inside the turbine casing, provided with a flange at the upper end that fits into the conical base of the female threaded section on the turbine casing by which it is assembled in the drill string, and which blocks the flange in position when it is screwed tight, and with a bent portion at the bottom end which projects close to the periphery of the turbine shaft and contains a-device to detect variations in magnetic flux, and a moving flux-variation inductor attached to the upper end of the turbine shaft and which operates with the detector, the electrical conductors inside the metal tube being connected at one end to the terminals on the detector and at the other end to a male plug which can be connected to a device to transmit signals from the bottom of the well to the surface.

In one embodiment of the invention, dismantling of I the detector for fitting to different models of turbines can be made simpler by fixing the male plug to the flange by means of one or more arms, the passages between which allow free flow of the drilling fluid under pressure driving the turbine.

In another embodiment of the invention, the device to detect variations in magnetic flux is a flexible blade relay, while the moving inductor is a magnetized bar. Each time the bar moves past the blade, the relay closes, creating impulses that can be used directly to measure the speed.

In another embodiment, the detector is a solenoid wound on a magnetized bar, and the inductor is a sim ple metal pin which causes periodical modifications in the flux supplied by the bar. Short electric impulses are produced in the solenoid and transmitted to electronic devices known in the previous art, where they are processed and counted.

The transmitting devices used with the speedmeasuring device according to the invention are known to a person skilled in the art, and can be obtained commercially under various'trade names.

The following description of two preferred embodiments of the invention will reveal the constructional details of the device, without other embodiments of the same features being in any way excluded.

FIG. 1 shows the lower part of the string of drilling rods, where a turbine is being used.

FIG. 2 shows a speed sensing device which can be fitted to the top of a drilling turbine, showing one embodiment of the detector.

FIG. 3 shows another embodiment of the detector.

In FIG. 1, a tool (I), which may be of the standard cutter-wheel type, a diamond tool or any other kind that can be used with a drilling turbine, is drilling a well (2), of uniform diameter.

The shaft (4) of the turbine (3), which drives the tool, carries a number of driving blades (6), as well as journals (8) and thrust-bearings (9).

The turbine casing remains fixed inside the well. It contains a number of guiding blades (5), journalbearings (7) and thrust-bearings (10). These joumalbearings and thrust-bearings are elastomer-coated, to ensure proper functioning in the drilling mud, despite the presence of solid particles in suspension.

Above the turbine (3) is the transmitting device l2), screwed directly on to the neck of the turbine or attached thereto by a short male coupling (11), which holds the turbine-speed sensor (13) embodying the present invention in position. All the connections between drill collars (14), transmitting device (12) and turbine (3) are standard connections, preferably with API standard threads. In one recommended embodiment, the sensor (13) fits into the space inside the coupling (11), with the lower end projecting into the top end of the turbine (3), where it operates in combination with the revolving shaft-end (4), supplying a signal representing the speed of the turbine. This signal is coded for transmission, in circuits (not shown here) inside the transmitting device (12).

FIG. 2 shows the speed-sensing device on a larger scale. The turbine casing ends at the top, level with the neck, in a female threaded section (1 5), to take the male end of a coupling (11), fixed to the transmitter (12), for assembly in the drill string. Depending on the model or the manufacturer, the top of the turbine may be cylindrical or have an indent for handling. In any case it has a female screw (15), with a conical base, for assembly in the drill string. The speed-sensing device rests on the conical base of this thflz'ad ed seam, by means of a flange (17 attached to a hub (34), into which the hermetic connecting tube (21) and male connecting plug (16) are screwed. This plug is of a type that can be fitted in mud or normal liquids. The hub (34) is attached to the flange (17) by arms (18), with passages between them to allow the mud driving the turbine to flow through under pressure. The hermetic connecting tube (21) has a threaded section (30), by which it is connected, by means of a centring component (19), to the bent length of tube (22). The length of this tube (21) and diameter of the centring component (19) are adapted to suit the particular type of turbines used. When a different model of turbine is to be used, either one or both of these components (19 and 21) have to be changed. This is easily done by withdrawing the sensing device from the turbine through the top, and replacing these components to suit the diameter and length of the new turbine.

The length of bent tube (22) carried by the centring component (19) contains the off-centered detector This is a relay with a flexible blade, which is sensitive to an external magnetic flux, supplied for instance by a magnet (25) fixed to the turbine shaft. For this purpose the magnet is in the shape of a bar, held in a small non-magnetic tube (24) screwed to the outside edge of a female screw (23), on the top of the turbine shaft (4). The sensing device functions as follows.

Each time the turbine revolves, the magnet excites the detector relay (20) as it passes close to it. The relay contacts are connected to the male plug (16) by leads (26) passing through the tubes (22 and 21). The signal thus obtained is transmitted to the appropriate electronic circuits in the transmitting device (12), through the female plug (28) and cable (29) fixed to the coupling (11). The signal is coded in the transmitting device, for transmission to the surface.

Installation of the sensing device is quite straightforward. The tube (21) and plug (16) are connected to the hub (34), with the result that the flange (l7) bears the weight of the whole device, so that it is only necessary to connect the male plug (16) to the female plug (28) on the ballast-rod coupling (11), and screw this coupling into the female screw on the turbine. While this is being done, the flange (17) carrying the weight of the whole sensing device (13) is pushed against the conical base of the threaded female section, and when the coupling is screwed tight, this automatically locks the unit in position, and in particular positions the detector (20) correctly in relation to the mobile fluxvariation inductor (25 or 33 in FIG. 3).

FIG. 3 shows another type of detector which can be used with the speed-sensing device shown in FIG. 2.

This involves an induced-flux variation detector consisting of a magnet (31 carrying a solenoid (32), and operating in combination with a pin (33) on the female screw (23). it operates as follows. Every time the shaft (4) revolves, the pin (33) passes close to the magnet (31), causing a momentary increase in the magnetic flux, and inducing a current in the solenoid (32). The impulse thus produced is conveyed by the leads and plug (16) to the appropriate circuits in the transmitting device (12).

The invention is not confined to the use of these types of detectors: without any departure from the spirit of the invention, it is possible to use capacityvariation detectors, or any type of detector capable of supplying a repeated signal or signals each time the turbine shaft revolves.

What is claimed is: 1. In a drilling assembly comprising a turbine, a turbine casing within which said turbine is rotatably mounted, said casing having an internally threaded frusto-conical upper end, a drill collar carrying electrical connector means and having a matingly frustoconical externally threaded lower end adapted to be screwed into the upper end of said casing, and a sensing device for measuring the speed of rotation of said turbine in said casing, the improved sensing device which comprises a supporting member shaped and dimensioned to be seated in the frusto-conical upper end of said turbine casing and gripped between said casing and the lower end of said drill collar,

a tube suspended from the central part of said supporting member to lie within said turbine casing,

spacer means on said tube beneath said supporting member for spacing said tube from said turbine casing,

sensor means at the bottom of said tube which responds to changes in magnetic field by providing an electric signal,

conductor means in said tube connected to said sensor means for carrying said signal to the upper end of said tube,

and electrical connector means at the upper end of said tube connected to said conductor means and adapted to interfit with the connector means carried by said drill collar.

2. A sensing device as claimed in claim 1 in which said supporting means is perforated to permit the passage therethrough of a fluid to drive said turbine.

3. A sensing device as claimed in claim 1 in which said sensor means is a flexible blade relay, the blade of which is magnetically actuated.

4. A sensing device as claimed in claim 1 in which said sensor means is a solenoid wound on a magnetized bar. 

1. In a drilling assembly comprising a turbine, a turbine casing within which said turbine is rotatably mounted, said casing having an internally threaded frusto-conical upper end, a drill collar carrying electrical connector means and having a matingly frusto-conical externally threaded lower end adapted to be screwed into the upper end of said casing, and a sensing device for measuring the speed of rotation of said turbine in said casing, the improved sensing device which comprises a supporting member shaped and dimensioned to be seated in the frusto-conical upper end of said turbine casing and gripped between said casing and the lower end of said drill collar, a tube suspended from the central part of said supporting member to lie within said turbine casing, spacer means on said tube beneath said supporting member for spacing said tube from said turbine casing, sensor means at the bottom of said tube which responds to changes in magnetic field by providing an electric signal, conductor means in said tube connected to said sensor means for carrying said signal to the upper end of said tube, and electrical connector means at the upper end of said tube connected to said conductor means and adapted to interfit with the connector means carried by said drill collar.
 2. A sensing device as claimed in claim 1 in which said supporting means is perforated to permit the passage therethrough of a fluid to drive said turbine.
 3. A sensing device as claimed in claim 1 in which said sensor means is a flexible blade relay, the blade of which is magnetically actuated.
 4. A sensing device as claimed in claim 1 in which said sensor means is a solenoid wound on a magnetized bar. 